The present invention relates to a compressor.
Japanese Laid-Open Patent Publication No. 2002-89437, for example, discloses a compressor having a housing in which a plurality of cylinder bores, a crank chamber, a suction chamber, and a discharge chamber are formed. The compressor is incorporated into a refrigeration circuit including an evaporator, a suction device, and a condenser. Each cylinder bore of the compressor accommodates a corresponding piston, while permitting the piston to reciprocate. A drive shaft rotatably supported by the housing is driven by an external drive source such as an engine. A swash plate is supported on the drive shaft rotatably in synchronization therewith. The swash plate is connected to the piston with pairs of hemispherical shoes. A sliding film is formed on a surface of the swash plate that slides upon a flat surface of the shoes. The sliding film is formed of a binder resin which contains a solid lubricant such as molybdenum disulfide.
When the drive shaft is driven by the external drive source, the swash plate rotates in synchronization therewith to cause each piston to reciprocate within the cylinder bore via the shoes. In each cylinder bore, a compression chamber is defined that changes in volume depending on reciprocating movement of a piston head. When the piston moves from the top dead center to the bottom dead center, a low pressure refrigerant gas is drawn into the compression chamber from the suction device connected to the evaporator in the refrigeration circuit. On the other hand, when the piston moves from the bottom dead center to the top dead center, a high pressure refrigerant gas is discharged into the discharge chamber from the compression chamber. The discharge chamber is connected to the condenser in the refrigeration circuit. The refrigeration circuit is used for air conditioning of a vehicle as an air conditioning system for a vehicle.
For this compressor, the sliding film applied to the surface of the swash plate allows the flat surface of the shoe to smoothly slide, thus preventing rattles of the swash plate and the shoes by wear of at least one of them or failures resulting from seizure therebetween.
In the conventional compressor, further improved sliding properties are desired under severe conditions such as where not only the surface of the swash plate and the flat surface of the shoes, but also a first sliding surface of a first member and a second sliding surface of a second member slide upon each other at high speed or under a relatively heavy load such as a high heat load. Particularly, when carbon dioxide is used as a refrigerant, the improved sliding properties are much desired. Thus, it can be considered to increase the content of solid lubricant, for example, to increase the content of molybdenum disulfide in the sliding film to 10% by mass or more and thereby improve seizure resistance between the first member and the second member. However, if the content of solid lubricant is increased, the solid lubricant will be apt to drop off of the film, resulting in increased wear depth of the sliding film.